Ongoing investigations of nervous system filaments, isolation and culture of neurons and oligodendroglia and myelin enzymes will be continued. We hope to resolve current problems on the composition of neurofilaments and glial filaments by a combination of chemical methods, including high resolution electrophoresis, peptide mapping and end group assays, and immunochemistry. Methods will be perfected for the isolation of oligo-endroglia from whole rat brain. These cells will be fully characterized and conditions will be perfected for their long-term maintenance in culture. Attempts will be made to culture neurons bulk-isolated in physiologic media. The membrane marker enzyme 5'-nucleotidase will be studied in purified myelin.